Orientador: José de Alencar Simoni / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T07:32:13Z (GMT). No. of bitstreams: 1 Riaz_Ali_D.pdf: 5855772 bytes, checksum: b17d5626ad22333e3c2a8cff516ddc1a (MD5) Previous issue date: 2014 / Resumo: Este trabalho apresenta a síntese e caracterização de compostos silsesquioxanos gaiola cúbica (POSS) com cadeias orgânicas pendentes. O projeto foi iniciado com a idéia de sintetizar os silsesquioxanos cúbicos com cadeias organofuncionalizadas ancoradas, capazes de capturar os metais pesados, corantes e CO2. Mas foram enfrentadas algumas dificuldades como baixo rendimento (30-37%) e longo tempo de reação (5-35 dias). As reações foram investigadas para melhorar o rendimento, bem como para reduzir o tempo de reação. Algumas modificações em rotas de reação foram introduzidas, o que trouxe melhorias notáveis nos resultados, onde o rendimento aumentou cerca de 64 % e o tempo de reação foi reduzido para 24 horas em média. Na sequência, os produtos sintetizados foram caracterizados para elucidar suas estruturas, utilizando diferentes técnicas físicas tais como FTIR, CHN, XRD, MEV, TGA, 13CNMR e 29SiNMR no estado sólido, onde as gaiolas Si-O de todos os compostos foram evidenciadas por meio de 29SiRMN e dos seus espectros de FTIR, enquanto as cadeias ancorados às gaiolas de POSS foram confirmadas utilizando os resultados de 13CRMN, juntamente com seus respectivos espectros de FTIR. Os compostos sintetizados também foram testados quanto à sua estabilidade térmica utilizando a técnica de TGA. Após a otimização da síntese de silsesquioxanos cúbicos, os híbridos PAA-13-3, PAA-MTC e PAA-Ph foram avaliados por suas habilidades de captação de cátions bivalentes, tais como Cu2+, Cd2+ e Pb2+ de suas soluções aquosas, sendo que o Cu2+ apresentou maior afinidade de sorção em relação aos dois metais. Estes sistemas de sorção foram analisados através ICP-OES. Para explicar o comportamento de sorção destas amostras alguns modelos estatísticos como Langmuir, Freundlich, Temkin e Redlich-Peterson foram aplicadas, onde os dados de sorção de Cu2+ em PAA-13-3 foram melhor ajustados pelo modelo Langmuir, mostrando ser uma sorção monocamada, enquanto que no caso do PAA-MTC e PAA-Ph modelo de melhor ajuste foi o Freundlich, confirmando a sorção de múlti camadas. Um dos materiais sintetizados (PAA-13-3) foi avaliado quanto à sua capacidade de adsorver CO2 gasoso, mostrando-se promissor na remoção de CO2, mesmo a baixas pressões (máx. 100 mm Hg). A adsorção de CO2 no material também foi estudada por calorimetria de adsorção gás-sólido, em um calorímetro especialmente desenvolvido para tal, observando-se valores de entalpia de adsorção entre -36 e -7 kJ mol-1 / Abstract: This report presents the synthesis and characterization of POSS compounds having cubic silsesquioxane cage to which the organic pendant chains are anchored. The project was started with the idea to synthesize the cubic silsesquioxanes with organofunctionalized pendant chains, which are able to capture heavy metals, dyes and some acids like CO2. But in the beginning the hurdles like low % yields (30-37 %) and long reaction times (5-35 days) were to be faced. The reactions were worked out to enhance the % yields as well as to reduce the reaction time. Some modifications in reaction routes have been introduced, which brought up remarkable improvements in the results, where yield was increased upto 64 % and reaction time was reduced to 1 day. All the synthesized products were then characterized for their structure elucidations using different physical techniques like FTIR, CHN, TGA, 13CNMR & 29SiNMR in solid state, where Si¿O cages of all compounds were elaborated through 29Si-NMR in solid state as well as through their respective FTIR patterns, while the pendant chains anchored to the POSS cages were confirmed using 13C-NMR results along with their respective FTIR spectra. The synthesized compounds were then tested for their thermal stability using the TGA technique. After optimizing the synthesis of cubic silsesquioxanes, hybrids PAA-13-3, PAA-MTC and PAA-Ph were worked out for their abilities of capturing divalent cations like Cu2+, Cd2+ and Pb2+ from their aqueous solutions, where Cu2+ showed higher affinity of sorption than other two bivalent metals. These sorption systems were analyzed using the ICP-OES. To explain the sorption behaviour of these samples some statistical models like Langmuir, Freundlich, Sips, Temkin and Redlich-Peterson were applied to the sorption data, where the data for Cu2+ on to PAA-13-3 was best fitted by Langmuir adsorption isotherm model showing the sorption to be monolayer, while in case of PAA-MTC and PAA-Ph Freundlich model was found to be a best fit, confirming multilayer sorption. One of the synthesized materials (PAA-13-3) was also evaluated for its ability to adsorb gaseous CO2 and was proved to be promising in removing CO2, even at low pressures (max. 100 mmHg). The adsorption of CO2 in the material is also studied by solid-gas adsorption calorimetry through a calorimeter especially developed for this system, where enthalpy of adsorption values were found to be between -7 and -36 kJ mol-1 / Doutorado / Quimica Inorganica / Doutor em Ciências

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This study investigates the extraction of hydrocarbons from oil sand using supercritical carbon dioxide (SC CO2). Experiments were carried out on three different types of oil sands. After some preliminary experiments, the feasibility of extracting hydrocarbons from oil sands by SC CO2 was confirmed and three experimental factors (pressure, temperature and mixing rate) were identified for further study. A two to the three factorial design was used to determine the significance of each factor and the significance of the interaction of the factors on the extraction efficiency. The extraction efficiency was calculated from Dean-Stark extraction analysis and was compared to the extraction efficiency based on gravimetric analysis. The results show that the extraction efficiency increased with pressure at a constant temperature. The effect of temperature on extraction efficiency is complex. The highest extraction efficiency was obtained at the high pressure (24.1MPa), high temperature (60C) and a mixing rate of 250rpm. / Environmental Science

The world we live in becomes more globalized as a result of new communication media. Communication occurs over greater distances which leads to increased travel. In the report AR5, by IPCC, it is showed that the human impact of climate change is clear and that something has to be done. Therefore its very important to change the human impact. A part of it is to change the way we travel within the service which leads to the purpose of the thesis. The purpose is to eximine how commune´s, in Gävleborgs län, choice of transport and with a change against virtual meetings affects greenhouse gas emissions and costs. An additional purpose is to gather information about currently known differences between natural and virtual meetings and explain these with a focus on interaction and communication. This is to give information about what it is that makes people feel that virtual meetings lack of communication . This has been done by studying the empirical results of the CERO-model and the NTM-database of greenhouse gas emissions and conduct a literature review relating to projects in the area of virtual meetings and then try to explain their results by learning and communication theories. The results clearly shows that train as vehicle is preferred both environmentally as financially and if the trip must be carried while driving or flying it is only justifiable when trains and public transport is disadvantaged. Virtual meetings are rather cheaper and more environmentally friendly than all vehicles but has some limitations. That is because the conversation becomes formal, and gesticulation and phonological patterns is missing. The restriction of virtual meetings can be explained with that contextual differences arise when individuals meet at great distances while communication requires a stricter meeting posture. / reser inom tjänsten vilket leder till syftet med examensarbetet som är att undersöka hur en kommuns val av färdmedel vid tjänsteresor samt vid ett skifte mot resfria möten påverkar samhället med avseende på växhusgasutsläpp och kostnad. Vidare är syftet att samla information om idag kända skillnader mellan fysiska och resfria möten och förklara dessa med fokus på interaktion och kommunikation. Detta för att ge information om vad det är som gör att en del känner att resfria möten brister i kommunikationen. Detta har gjorts genom att studera empiriska resultat av CERO-modellen och NTMs databas för växthusgasutsläpp samt genomföra en litteraturstudie av projekt inom området resfria möten, för att förklara deras resultat utifrån lärande- och kommunikationsteorier. Resultatet visar tydligt på att tåget som färdmedel både är att fördedra miljömässigt såsom ekonomiskt om resan måste genomföras medan bil och flyg endast är försvarbart då utbredningen av tåg och kollektivtrafik är missgynnad. Resfria möten är istället billigare och miljövänligare än alla färdmedel men har vissa begränsningar då samtalet blir formellt och saknar gestikulering samt fonologiska mönster. Att resfria möten har begränsningar kan förklaras i att kontextuella skillnader uppstår när individer möts på stora avstånd samtidigt som kommunikationen kräver en striktare möteshållning.

Der rapide Anstieg der Bevölkerung führt zu einer dramatischen Zunahme des Brennstoff- und Energiebedarfs. Längerfristig kann die nachhaltige Energieversorgung der Menschheit nur durch erneuerbare Energiequellen gewährleistet werden. Dies motiviert die Bemühungen um alternative, sauberere Brennstofftechnologien wie z.B. die Erzeugung von Wasserstoff. Diese Arbeit untersucht die Verbesserung der optoelektronischen Eigenschaften von Silizium Photokathoden, durch optische Nanostrukturen, die die Reflexion mittels optischer Resonanzen reduzieren. Wir konzentrieren uns dabei auf die Entwicklung von Nanostrukturen , die optische Konzepte wie Mie-Resonanzen und periodische Indexprofilierung nutzen. Um diese optischen Nanostrukturen zu realisieren, verwenden wir zwei Herstellungsverfahren. Die Verfahren werden durch einen iterativen Ansatz optimiert, um zu den Nanostrukturen mit den gewünschten optischen Eigenschaften zu gelangen. Die erste Art von Nanostrukturen gehört zur Klasse der Meta-Oberflächen (Metasurfaces) und wird durch Elektronenstrahl- Lithographie und Top-Down-Herstellung implementiert. Die optischen Spektren dieser Strukturen werden dann mit Hilfe von Simulation und Experimenten eingehend untersucht. Die zweite Art von Nanostrukturen basiert auf Änderungen des Brechzahlprofils von dielektrischen periodischen Nanostrukturen. Diese Strukturen werden durch Maskenlithographie mittels Polystyrol-Kugeln hergestellt. Auch bei diesen Strukturen werden die optischen Eigenschaften vermessen und ihre physikalischen Bedeutung mit Hilfe von numerischen Simulationen analysiert. Um den Einfluss dieser Strukturen auf die Kurzschlussstromdichten von Silizium Photokathoden zu demonstrieren, charakterisieren wir den Photostrom, der über einen Silizium-Elektrolyt-pn-Übergang mit und ohne Nanostrukturen gemessen wird. Zusammenfassend stellen wir einen Vergleich der Antireflexionseigenschaften der beiden entwickelten Strukturen sowie eine Verbesserung der photoelektrochemischen Funktionalität vor. Daraus leiten wir Ideen für zukünftige Oberflächendesigns ab, welche die noch bestehenden Nachteile beider Strukturen überwinden. / Global fuel and energy demands continue to increase due to the rapid rise in population and the dependence of this increasing population on exisiting energy resources for its sustainance. This has led to efforts in developing cleaner fuel sources such as hydrogen generation. This thesis focuses on demonstrating the optical benefit of nanostructures to improve the optoelectronic functioning of silicon photocathodes which aid in hydrogen generation via nanostructured antireflection. We lay our focus on the development of nanostructures which utilise optical concepts such as Mie type resonances based on metasurfaces and periodic index profiling. Computational design is used to obtain structure parameters for achieving desired effects. To implement these optical effects we take aid of two methods of fabrication. These fabrication methods are optimised via iterative trials to arrive at nanostructures of high quality. The first type of nanostructures belong to the metasurface class. These are implemented by e-beam lithography and top down processing. The optical spectra are then comapred with aid of simulation and experiments. The second type of nanostructures belong to the class of gradually varying periodic nanostructures. We obtain these via iterative fabrication using colloidal mask lithography. In a subsequent step we analyse experimentally their optical spectra and with aid of simulations analyse their physical implication. To demonstrate an optical benefit of these structures on enhancing the short circuit current densities of silicon photocathodes, we characterise the photocurrent measured across the silicon-electrolyte pn-junction with and without nanostructures and evaluate this increase. In conclusion, we provide a comparison of the antireflection properties offered by the two developed structures as well as in terms of improving photoelectrochemical environment. As an outlook, we propose ideas to overcome the existing drawbacks of both structures.

As florestas tropicais representam grande parte do carbono armazenado na forma de biomassa. São caracterizadas por uma alta taxa de produtividade primária, no entanto, não é muito claro o entendimento de como as florestas tropicais respondem ao balanço de carbono com o avanço das mudanças climáticas. Um dos efeitos relacionados ao aumento de concentração de dióxido de carbono na atmosfera e ao aumento da temperatura ambiental, que pode contribuir para ocorrência de distúrbios na função de assimilação ou emissão deste composto dentro das florestas tropicais, é a temperatura. A temperatura tem sido apontada, como influenciadora nas trocas gasosas das plantas, afetando a fotossíntese e a respiração. Neste sentido, estudos que visam melhorar o entendimento dos processos fisiológicos das plantas, principalmente os que estão envolvidos com a ciclagem do C, são importantes para gerar informações sobre os efeitos das mudanças globais nos padrões de respostas da assimilação de CO2 das plantas ou ecossistemas. O objetivo deste trabalho foi determinar as respostas dos processos de fotossíntese e respiração em função da temperatura foliar de um indivíduo e comunidade em estudo. O trabalho foi desenvolvido na Floresta Nacional (FLONA) dos Tapajós (2º 51 Sul (S), 54º 58 Oeste (O)) localizada ao sul da cidade de Santarém, próximo ao marco km 67 e 83 da rodovia Santarém-Cuiabá BR-163. Para realização das medidas nas folhas das plantas na copa do dossel florestal foram utilizadas cinco torres. Para quantificação da fotossíntese e respiração foliar, utilizou-se um analisador de gás por infravermelho (IRGA) modelo (LI- 6400). Para cada folha observada, obteve-se uma curva de resposta da fotossíntese à radiação fotossinteticamente ativa (A-RFA) e quatro curvas de respostas da fotossíntese em relação a concentração interna de CO2 (A-Ci), em quatro grupos de temperaturas foliares (Tfoliar). As curvas de resposta a radiação fotossinteticamente ativa (RFA), Tfoliar e concentração interna de CO2 (Ci) foram realizadas entre os horários de 07:00 e 14:00 horas. Para o ciclo diurno quantificou-se a fotossíntese (A), condutância estomática (gs), transpiração (E) e déficit de pressão de vapor da folha (DPVf), as medidas foram realizadas ao longo de um dia entre 10:00 e 18:00 horas. A temperatura ótima média da fotossíntese foi de 29,9 oC, e a população apresentou taxa assimilatória líquida ótima de CO2 de 7,2 µmol.m-2.s-1. Valores de temperaturas foliares superiores a 32,9 oC e 32,5 oC, diminuíram a capacidade máxima de transporte de elétrons e a velocidade máxima de carboxilação, respectivamente. A eficiência de carboxilação começou a diminuir a partir de 31 oC. A concentração interna de CO2 diminuiu 32,6% aos 42 oC. Na avaliação do ciclo diurno A e gs decresceram significativamente a partir das 16:00 e 15:00 horas, respectivamente. Quando houve um aumento de 0,34 kPa no DPVf a transpiração diminuiu em 64%. A condutância estomática decresceu com o aumento da temperatura foliar e a respiração foliar foi positivamente relacionada com o aumento da temperatura foliar. / Tropical forests hold large stores of carbon as biomass. They are characterized by large net primary productivity, however, it is not well understood how carbon budgets of tropical forests respond to the advance of climatic changes. Temperature is one of the agents related to the increase of carbon dioxide concentration in the atmosphere and ambient temperatures can contribute to alterations in assimilation or emission of CO2 in tropical forests. Temperature has been pointed as responsible for gas exchange rates in plants, affecting the photosynthesis and respiration. Thus, studies aimed at better understanding of physiological processes of plants, particularly those which involve carbon cycling, are important to generate information on the effects of the global changes in the trends of CO2 assimilation response in plants or in ecosystems. The objective of this work was to determine the photosynthesis processes and respiration responses as a function of leaf temperature of an individual and of the community in study. The study was carried out at the Tapajós National Forest (FLONA, 2º 51` S 54º 58` W) located in the south of Santarém municipality, at kms 67 and 83 of the Santarém- Cuiabá highway (BR-163). Five towers were used to support measurements in leaves in the forest canopy. An infra-red gas analyzer (IRGA, LI-6400 model) was utilized for quantification of leaf photosynthesis and respiration. For each observed leaf, a curve relating the photosynthesis response to the photosynthetically active radiation (PAR) was obtained together with four curves of photosynthesis response in relation to the internal CO2 concentration (Ci) in four groups of leaf temperatures (Tleaf). The response curves of PAR, Tleave and internal CO2 concentration (Ci) were obtained between 07h00 and 14h00. For the diurnal cycle it was quantified photosynthesis (A), stomatal conductance (gs), transpiration (E) and vapor pressure deficit of the leaf (VPDf), and measurements were carried out throughout one day between 10h00 and 18h00. The main optimum temperature of photosynthesis was 29.9 °C, and the community presented optimum CO2 net assimilation rate of 7.2 µmol.m-2.s-1. Leaf temperature values above 32.9 °C and 32.5 °C decreased the maximum capacity of electron transport and the maximum speed of carboxylation, respectively. The carboxylation efficiency starts to decreased at 31 °C. The internal CO2 concentration diminished 32.6% at 42 °C In the evaluation of the diurnal cycle, photosynthesis and stomatal conductance decreased significantly after 16h00 and 15h00 hours, respectively. An increase of 0.34 kPa in VPDf diminished transpiration in 64%. The stomatal conductance decreased with increase of leaf temperature and leaf respiration was positively related to the increase of leaf temperature.

<p>This essay aims at giving some insights in the complex relationship of increased greenhouse gases (GHG) in the atmosphere, the emission of carbon dioxide from the transport sector and different ways to decrease the contributions of heavy road transport to greenhouse gases. Road transport using heavy trucks is a large contributor to GHG. The objective of this study is to evaluate from a business perspective some existing alternatives for truck fuel and how these influence the total amount of GHG – emission. I have chosen to analyse if the commerce of carbon credits (Kyoto) could influence the speed of transition to alternative fuels. A comparison is presented including cost and environmental issues for the fuels such as ethanol and diesel.</p><p>Petroleum diesel is the dominant fuel used by heavy trucks and this is due to high costs and lack of availability of alternative fuel types.</p><p>The results show that a transition from diesel to alternative fuel is not possible in the near future unless a strong political control (steering, leadership) or big change on the conditions takes place. The actual price for emission rights is not high enough to influence a company’s choice of fuel if the transport sector would join the scheme. The price of emission rights needs to increase sharply in order to be able to influence the choice of fuel and technique. In the foreseeable future this is not a realistic event.</p><p>Transport companies with a long term strategy and a proactive environmental policy for transition to alternative fuels are seen as role models by customers and would also give a competitive advantage. My study shows that ethanol is a possible alternative to diesel if the transport sector can exploit its environmental, economical and social advantages.</p><p>The study also indicates that the current alternative fuel market is too weak for a change. A final solution for the transition to alternative fuel can occur either by a strong political leadership to the expense of higher transportation prices for customers or if a new competitive technology for alternative fuels will be viable. Of course, combinations of these alternatives are also possible.</p> / <p>Denna uppsats vill ge en inblick i det komplexa sammanhanget rörande ökade växthusgaser i atmosfären, transportsektorns koldioxidutsläpp, och olika sätt att minska de tunga vägtransporternas påverkan på klimatet. Syftet med studien är att utvärdera olika alternativ och sätt att styra mot minskade utsläpp av växthusgaser inom transportsektorn. Lösningarna kan vara av olika karaktär som politiska, teknologiska eller organisatoriska. Jag har valt att undersöka hur handeln med utsläppsrätter kan påskynda övergången till alternativa bränslen. Därmed har jag valt att jämföra kostnader och miljöaspekter för olika bränsleslag som etanol, diesel och bränsleceller för en tung lastbil.</p><p>Som ett exempel för tranportnäringen har jag valt transportföretaget DHL. Företaget använder transportmedel som väg, flyg, fartyg och järnväg men endast tunga lastbilar undersöks eftersom det är dessa som orsakar de största utsläppen av koldioxid. I dagsläget är diesel helt dominerande som bränsle för de tunga lastbilarna och detta förklaras av högre kostnader och/eller sämre tillgänglighet för andra bränsle alternativ.</p><p>Studiens resultat tyder på att en övergång från fossila till alternativa bränslen som ger mindre miljöpåverkan inte kommer att gå snabbt utan politisk styrning. Handeln med utsläppsrätter med priser på dagens nivå har ringa eller ingen påverkan på valet av framtida teknik och bränsle. För att handeln med utsläppsrätter ska kunna påverka ett tranportföretags val av teknik och bränsle måste priset mångdubblas, vilket inte är realistisk inom överskådlig framtid. Bränsleceller kan vara ett intressant alternativ på lång sikt.</p><p>Transportföretag som tänker långsiktigt och har en proaktiv miljöpolicy för övergång till alternativa bränslen ses som förebilder av allmänheten och sina kunder, de har därför en konkurrensfördel. Studien visar dessutom att etanol är ett intressant alternativ till diesel som transportbranschen kan utnyttja i större omfattning inom en nära framtid. Det finns förutom miljö- och ekonomiska fördelar även sociala aspekter som motiverar ökad användning av etanol.</p><p>Tropiska och subtropiska länder som har tillgång till stora arealer outnyttjade eller sparsamt utnyttjade jordbruksmarker kan odla sockerrör (råvarubas för etanolframställning) och skapar därmed ökade arbetstillfällen och ökad ekonomisk tillväxt. Det finns tillgänglig teknik som skulle kunna ersätta de flesta fossila bränsleslag men det saknas fortfarande tillräckligt ”tryck” från samhället. Marknadskrafterna är inte tillräckligt starka. Ett definitivt genomslag för alternativa bränslen kommer först då en tillräcklig kraftig politisk styrning sker.</p>

This essay aims at giving some insights in the complex relationship of increased greenhouse gases (GHG) in the atmosphere, the emission of carbon dioxide from the transport sector and different ways to decrease the contributions of heavy road transport to greenhouse gases. Road transport using heavy trucks is a large contributor to GHG. The objective of this study is to evaluate from a business perspective some existing alternatives for truck fuel and how these influence the total amount of GHG – emission. I have chosen to analyse if the commerce of carbon credits (Kyoto) could influence the speed of transition to alternative fuels. A comparison is presented including cost and environmental issues for the fuels such as ethanol and diesel. Petroleum diesel is the dominant fuel used by heavy trucks and this is due to high costs and lack of availability of alternative fuel types. The results show that a transition from diesel to alternative fuel is not possible in the near future unless a strong political control (steering, leadership) or big change on the conditions takes place. The actual price for emission rights is not high enough to influence a company’s choice of fuel if the transport sector would join the scheme. The price of emission rights needs to increase sharply in order to be able to influence the choice of fuel and technique. In the foreseeable future this is not a realistic event. Transport companies with a long term strategy and a proactive environmental policy for transition to alternative fuels are seen as role models by customers and would also give a competitive advantage. My study shows that ethanol is a possible alternative to diesel if the transport sector can exploit its environmental, economical and social advantages. The study also indicates that the current alternative fuel market is too weak for a change. A final solution for the transition to alternative fuel can occur either by a strong political leadership to the expense of higher transportation prices for customers or if a new competitive technology for alternative fuels will be viable. Of course, combinations of these alternatives are also possible. / Denna uppsats vill ge en inblick i det komplexa sammanhanget rörande ökade växthusgaser i atmosfären, transportsektorns koldioxidutsläpp, och olika sätt att minska de tunga vägtransporternas påverkan på klimatet. Syftet med studien är att utvärdera olika alternativ och sätt att styra mot minskade utsläpp av växthusgaser inom transportsektorn. Lösningarna kan vara av olika karaktär som politiska, teknologiska eller organisatoriska. Jag har valt att undersöka hur handeln med utsläppsrätter kan påskynda övergången till alternativa bränslen. Därmed har jag valt att jämföra kostnader och miljöaspekter för olika bränsleslag som etanol, diesel och bränsleceller för en tung lastbil. Som ett exempel för tranportnäringen har jag valt transportföretaget DHL. Företaget använder transportmedel som väg, flyg, fartyg och järnväg men endast tunga lastbilar undersöks eftersom det är dessa som orsakar de största utsläppen av koldioxid. I dagsläget är diesel helt dominerande som bränsle för de tunga lastbilarna och detta förklaras av högre kostnader och/eller sämre tillgänglighet för andra bränsle alternativ. Studiens resultat tyder på att en övergång från fossila till alternativa bränslen som ger mindre miljöpåverkan inte kommer att gå snabbt utan politisk styrning. Handeln med utsläppsrätter med priser på dagens nivå har ringa eller ingen påverkan på valet av framtida teknik och bränsle. För att handeln med utsläppsrätter ska kunna påverka ett tranportföretags val av teknik och bränsle måste priset mångdubblas, vilket inte är realistisk inom överskådlig framtid. Bränsleceller kan vara ett intressant alternativ på lång sikt. Transportföretag som tänker långsiktigt och har en proaktiv miljöpolicy för övergång till alternativa bränslen ses som förebilder av allmänheten och sina kunder, de har därför en konkurrensfördel. Studien visar dessutom att etanol är ett intressant alternativ till diesel som transportbranschen kan utnyttja i större omfattning inom en nära framtid. Det finns förutom miljö- och ekonomiska fördelar även sociala aspekter som motiverar ökad användning av etanol. Tropiska och subtropiska länder som har tillgång till stora arealer outnyttjade eller sparsamt utnyttjade jordbruksmarker kan odla sockerrör (råvarubas för etanolframställning) och skapar därmed ökade arbetstillfällen och ökad ekonomisk tillväxt. Det finns tillgänglig teknik som skulle kunna ersätta de flesta fossila bränsleslag men det saknas fortfarande tillräckligt ”tryck” från samhället. Marknadskrafterna är inte tillräckligt starka. Ett definitivt genomslag för alternativa bränslen kommer först då en tillräcklig kraftig politisk styrning sker.

As florestas tropicais representam grande parte do carbono armazenado na forma de biomassa. São caracterizadas por uma alta taxa de produtividade primária, no entanto, não é muito claro o entendimento de como as florestas tropicais respondem ao balanço de carbono com o avanço das mudanças climáticas. Um dos efeitos relacionados ao aumento de concentração de dióxido de carbono na atmosfera e ao aumento da temperatura ambiental, que pode contribuir para ocorrência de distúrbios na função de assimilação ou emissão deste composto dentro das florestas tropicais, é a temperatura. A temperatura tem sido apontada, como influenciadora nas trocas gasosas das plantas, afetando a fotossíntese e a respiração. Neste sentido, estudos que visam melhorar o entendimento dos processos fisiológicos das plantas, principalmente os que estão envolvidos com a ciclagem do C, são importantes para gerar informações sobre os efeitos das mudanças globais nos padrões de respostas da assimilação de CO2 das plantas ou ecossistemas. O objetivo deste trabalho foi determinar as respostas dos processos de fotossíntese e respiração em função da temperatura foliar de um indivíduo e comunidade em estudo. O trabalho foi desenvolvido na Floresta Nacional (FLONA) dos Tapajós (2º 51 Sul (S), 54º 58 Oeste (O)) localizada ao sul da cidade de Santarém, próximo ao marco km 67 e 83 da rodovia Santarém-Cuiabá BR-163. Para realização das medidas nas folhas das plantas na copa do dossel florestal foram utilizadas cinco torres. Para quantificação da fotossíntese e respiração foliar, utilizou-se um analisador de gás por infravermelho (IRGA) modelo (LI- 6400). Para cada folha observada, obteve-se uma curva de resposta da fotossíntese à radiação fotossinteticamente ativa (A-RFA) e quatro curvas de respostas da fotossíntese em relação a concentração interna de CO2 (A-Ci), em quatro grupos de temperaturas foliares (Tfoliar). As curvas de resposta a radiação fotossinteticamente ativa (RFA), Tfoliar e concentração interna de CO2 (Ci) foram realizadas entre os horários de 07:00 e 14:00 horas. Para o ciclo diurno quantificou-se a fotossíntese (A), condutância estomática (gs), transpiração (E) e déficit de pressão de vapor da folha (DPVf), as medidas foram realizadas ao longo de um dia entre 10:00 e 18:00 horas. A temperatura ótima média da fotossíntese foi de 29,9 oC, e a população apresentou taxa assimilatória líquida ótima de CO2 de 7,2 µmol.m-2.s-1. Valores de temperaturas foliares superiores a 32,9 oC e 32,5 oC, diminuíram a capacidade máxima de transporte de elétrons e a velocidade máxima de carboxilação, respectivamente. A eficiência de carboxilação começou a diminuir a partir de 31 oC. A concentração interna de CO2 diminuiu 32,6% aos 42 oC. Na avaliação do ciclo diurno A e gs decresceram significativamente a partir das 16:00 e 15:00 horas, respectivamente. Quando houve um aumento de 0,34 kPa no DPVf a transpiração diminuiu em 64%. A condutância estomática decresceu com o aumento da temperatura foliar e a respiração foliar foi positivamente relacionada com o aumento da temperatura foliar. / Tropical forests hold large stores of carbon as biomass. They are characterized by large net primary productivity, however, it is not well understood how carbon budgets of tropical forests respond to the advance of climatic changes. Temperature is one of the agents related to the increase of carbon dioxide concentration in the atmosphere and ambient temperatures can contribute to alterations in assimilation or emission of CO2 in tropical forests. Temperature has been pointed as responsible for gas exchange rates in plants, affecting the photosynthesis and respiration. Thus, studies aimed at better understanding of physiological processes of plants, particularly those which involve carbon cycling, are important to generate information on the effects of the global changes in the trends of CO2 assimilation response in plants or in ecosystems. The objective of this work was to determine the photosynthesis processes and respiration responses as a function of leaf temperature of an individual and of the community in study. The study was carried out at the Tapajós National Forest (FLONA, 2º 51` S 54º 58` W) located in the south of Santarém municipality, at kms 67 and 83 of the Santarém- Cuiabá highway (BR-163). Five towers were used to support measurements in leaves in the forest canopy. An infra-red gas analyzer (IRGA, LI-6400 model) was utilized for quantification of leaf photosynthesis and respiration. For each observed leaf, a curve relating the photosynthesis response to the photosynthetically active radiation (PAR) was obtained together with four curves of photosynthesis response in relation to the internal CO2 concentration (Ci) in four groups of leaf temperatures (Tleaf). The response curves of PAR, Tleave and internal CO2 concentration (Ci) were obtained between 07h00 and 14h00. For the diurnal cycle it was quantified photosynthesis (A), stomatal conductance (gs), transpiration (E) and vapor pressure deficit of the leaf (VPDf), and measurements were carried out throughout one day between 10h00 and 18h00. The main optimum temperature of photosynthesis was 29.9 °C, and the community presented optimum CO2 net assimilation rate of 7.2 µmol.m-2.s-1. Leaf temperature values above 32.9 °C and 32.5 °C decreased the maximum capacity of electron transport and the maximum speed of carboxylation, respectively. The carboxylation efficiency starts to decreased at 31 °C. The internal CO2 concentration diminished 32.6% at 42 °C In the evaluation of the diurnal cycle, photosynthesis and stomatal conductance decreased significantly after 16h00 and 15h00 hours, respectively. An increase of 0.34 kPa in VPDf diminished transpiration in 64%. The stomatal conductance decreased with increase of leaf temperature and leaf respiration was positively related to the increase of leaf temperature.

Jordens befolkning behöver kraftigt reducera koldioxidutsläppen till atmosfären för att förhindra klimatförändringar. Klimatmål har sats upp av unioner och länder där de bland annat vill förhindra en global temperaturökning över 1.5 grader. För att uppnå dessa klimatmål menar forskare och institutioner på att stora mängder koldioxid kommer att behöva avskiljas vid utsläppskällor och lagras geologiskt (eng. carbon capture storage, förkortad CCS). I Sverige har ett fåtal CCS-projekt tagit fart men CCS är fortfarande inte kommersiellt tillgängligt. Frågeställningen för det här arbetet var därför: vilka är de mest relevanta utmaningar som kommersiellt tillgänglig CCS står inför idag i Sverige?Metoderna som användes var en litteraturstudie och tre\newline intervjuer. Personerna som intervjuades var en forskare från Chalmers Tekniska högskola, en chef från företaget Stockholm Exergi och en civilingenjör från projektet Northern lights. Utmaningarna delades in i kategorierna: tekniska-, politiska-, ekonomiska- och övriga utmaningar, för att enklare identifieras och jämföras. Resultaten visade att det fanns utmaningar i samtliga kategorier. Den tekniska utmaningen låg framförallt i att bygga upp och anpassa den tillgängliga CCS-tekniken till olika tillämpningsbara industrier. Politiskt var utmaningen främst att övertyga politiker att satsa på CCS, men också att införskaffa tillräckligt stora ekonomiska styrmedel, incitament och investeringar. Detta eftersom de som existerar idag antingen saknades helt eller ansågs vara för små. De ekonomiska utmaningarna var att stimulera investerare samt att bygga upp en fungerande och hållbar ekonomisk plan för CCS. I kategorin övriga utmaningar var den främsta utmaningen att övertyga befolkningen och att sprida kunskap kring CCS och dess potential. Avgränsningar i det här arbetet var framförallt bristen på resurser och tid. Fler intervjuer och en djupare litteraturstudie hade varit önskvärd för att fördjupa studien men begränsades av tid och möjligheter för kursens omfattning. / The world population need to reduce its carbon dioxide emissions to the atmosphere in order to prevent a climate change. Climate targets have been set by unions and countries to reduce carbon dioxide emissions before the average temperature rise exceeds 1.5 degrees Celsius. To achieve these climate goals, researchers and institutions believe large amounts of carbon dioxide needs to be stored below ground (carbon capture storage, abbreviated CCS). In Sweden have a small number of projects taken off, but CCS is still not commercially available. The question for this work was therefore: what are the most relevant challenges that commercially CCS currently faces in Sweden?The methods used were a literature study and three interviews.The persons interviewed were a researcher from Chalmers Tekniska university, a manager from the company Stockholm Exergi and an engineer from the Northern Lights project. The challenges were divided into four categories: technical-, political-, economic-, and other challenges, to make it easier to identify and compare. Results showed that there were challenges in all four categories. The technical challenge was mainly to build and adapt the available CCS technology to different types of industries. Politically, the challenge was primarily to increase their interest and support towards CCS. This along with the challenge of acquiring financial instruments, incentives and investments that was currently lacking or was too small. The economic challenges were to stimulate investors from both private and political quarters and to organize and operate a functioning and sustainable financial plan. In the category other challenges, the most mentioned challenge was convincing the population and to spread knowledge about CCS and its potential. Delimitations in this work was above all the lack of resources and time. More interviews anda deeper literature study would have been desirable to deepen the study but was limited by time and opportunities for the scope of the course.